Hydroxide borate esters

L-Ascorbic acid was used as a precursor for chiral building blocks via its convenient transformation to (S)-2,3-O-isopropylideneglyceraldehyde 285 (80JA6304 82H327 86T447) (Scheme 58). Thus, the acetonide in a multi-step, one-pot procedure was treated with sodium borohydride, which presumably reduces the ene-diol, followed by cleavage of the borate ester and the lactone ring with excess sodium hydroxide. This was fol-... 

Hydroxide anion attacks the boron atom of the borate ester. 

Additive FRs are introduced during a subsequent compounding stage. These include chlorinated paraffins, brominated organics, phosphate esters, aluminium trihydrate, magnesium hydroxide, borates, and antimony trioxide. 

CxH Hg02, 62-38-4) see Phenylmcrcuric borate phenylmercuric hydroxide (C H HgO 100-57-2) see Phenylmercuric borate JV-[(phenylmethoxy)carbonylJ-DL-homocysteine acetate (ester)... 

Synthesis of functional models of carbonic anhydrase has been attempted with the isolation of an initial mononuclear zinc hydroxide complex with the ligand hydrotris(3-t-butyl-5-methyl-pyrazolyl)borate. Vahrenkamp and co-workers demonstrate the functional as well as the structural analogy to the enzyme carbonic anhydrase. A reversible uptake of carbon dioxide was observed, although the unstable bicarbonate complex rapidly forms a dinuclear bridged complex. In addition, coordinated carbonate esters have been formed and hydrolyzed, and inhibition by small ions noted.462 A number of related complexes are discussed in the earlier Section 6.8.4. 

There have been two reports of patients scheduled for tonometry who developed periorbital dermatitis following the topical instillation of local anesthetic eye drops (4). The first patient reacted strongly positive on patch testing to Thilorbin AT (oxybuprocaine, fluorescein, phenylmercuric borate, polysorbate 20, mannitol) and also to oxybuprocaine alone. The second reacted to Conjucain EDO (oxybuprocaine, sorbitol, sodium hydroxide) and to oxybuprocaine alone. The authors believed these to be the only described cases of a delayed hjrpersensitivity reaction to oxybuprocaine, an ester local anesthetic commonly used for topical anesthesia in the eye. 

Kinetic studies of reactions of three tris(pyrazolyl)borate-ligated zinc hydroxide complexes ([(TpR,Me)Zn-OH], Fig. 42, top) with triorganophosphate ester substrates in chloroform provided evidence for a concerted or hybrid-type mechanism.96 The reactions under study in this case are stoichiometric (Fig. 42, bottom) and involve generation of 4-nitrophenol (Rr// = 0C6H4-/>-N02). Notably, this acidic phenol rapidly undergoes reaction with the starting [(TpR,Me)Zn-OH] complex to yield [(TpR,Me)Zn-0C6H4-/ -N02] derivatives. This second reaction is at least... 

Commercial chemical fibers are combustible in nature, and improved FR properties must be considered in actual application. Most FR additives contain bromine (Br), chlorine (Cl), phosphorus (P), antimony, or aluminum. Among them, commonly used additives are additive brominated hydrocarbons and reactive brominated hydrocarbons, nonhalogenated phosphate esters, halogenated phosphate esters, trioxide antimony oxide, pentoxide antimony oxide and sodium derivatives, chlorinated hydrocarbons like chlorinated paraffin, and chlorinated cycloaUphatics. Others include chlorinated or brominated compounds, fluorinated compounds, magnesium carbonate, magnesium hydroxide, melamine, molybdenum compounds, silicone polymer, and zinc borate. Sometimes, polymers are chemically modified, and N, P, Cl, fluorine (F), silicon (Si), and Br elements can be introduced into the polymer main chain [49]. 

Phosphata Ester Oils (C) Potassium Bicarbonate IBI Potassium Borate IC) Potassium Bromids (C) Potassium Carbonate IS) Potassium Chlorate (C) Potassium Chloride (C) Potssium Chromate (SI Potassium Cyanide (C) Potassium Oichromate (S) Potassium Ferricyanide IS) Potassium Hydroxide (SI Potassium Hypochlorite IS) Potassium Nitrate (Cl Potassium Oxalate IS) Potassium Permanganate IS) Potassium Sulfate IC) Potassium Sulfite ( 1 Prtstone (C)... 

Phosphate esters, halogenated phosphorus compounds, chlorinated paraffins, aluminum hydroxide, antimony oxide, zinc borate... 

Also obtained (poor yield) by reaction of benzoyl chloride with m-tolyl borate in the presence of aluminium chloride in refluxing carbon disulfide for 2 h (5%) [55]. Preparation by acylation of m-tolyl benzoate with benzoyl chloride in the presence of zinc chloride at 130° for 1 h, followed by saponification of the p-keto ester so formed with sodium hydroxide in boiling ethanol [637]. 

Additives that impart smoke-suppressant properties to a composition tend not to be flame retardant. Conventional flame retardant and smoke-suppressant formulations include phosphorus-containing compounds such as a phosphoric acid ester, ammonium poly(phosphate) and red phosphorus, or halogen containing compounds such as tetrabromobisphenol A, decabromodiphenyl oxide and chlorinated polymers, and metal compounds such as magnesium hydroxide, aluminum hydroxide and zinc borate (4). 

There are several fillers that impart flame-retardant properties to mbber compounds. These are magnesium hydroxide, Versamag or Zerogen 50 magnesium carbonate, Elastocarb or Magcarb L zinc borate, Firebrake ZB alumina trihydrate, Micral and antimony oxide, Fireshield H, L, UF or Synpro-Ware R321. These are used primarily with NBR/PVC blends with chlorinated paraffins and/or phosphate ester plasticizers and mineral fillers for flame-resistant applications. 

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